Error connecting to Slack IRC gateway

Question

I'm using the cl-irc library to connect to Slack, via the IRC gateway Slack provides.

However I'm getting the following error when I try to start the message loop with read-message-loop:

error while parsing arguments to DESTRUCTURING-BIND:
  invalid number of elements in
    ("duncan_bayne" "Welcome" "to" "Slack" "IRC" "Gateway"
     "server" "duncan_bayne!~duncan_bayne@1.2.3.4")
  to satisfy lambda list
    (CL-IRC:NICKNAME CL-IRC::WELCOME-MESSAGE):
  exactly 2 expected, but 8 found
   [Condition of type SB-KERNEL::ARG-COUNT-ERROR]

... 

Backtrace:
  0: ((:METHOD CL-IRC::DEFAULT-HOOK (CL-IRC:IRC-RPL_WELCOME-MESSAGE)) #<CL-IRC:IRC-RPL_WELCOME-MESSAGE irc.tinyspeck.com RPL_WELCOME {1007FC6293}>) [fast-method]
  1: ((:METHOD CL-IRC::APPLY-TO-HOOKS (T)) #<CL-IRC:IRC-RPL_WELCOME-MESSAGE irc.tinyspeck.com RPL_WELCOME {1007FC6293}>) [fast-method]
  2: ((:METHOD CL-IRC:IRC-MESSAGE-EVENT (T CL-IRC:IRC-MESSAGE)) #<unavailable argument> #<CL-IRC:IRC-RPL_WELCOME-MESSAGE irc.tinyspeck.com RPL_WELCOME {1007FC6293}>) [fast-method]
  3: ((:METHOD CL-IRC:READ-MESSAGE (CL-IRC:CONNECTION)) #<CL-IRC:CONNECTION myob.irc.slack.com {10068E8ED3}>) [fast-method]
  4: ((:METHOD CL-IRC:READ-MESSAGE-LOOP (T)) #<CL-IRC:CONNECTION myob.irc.slack.com {10068E8ED3}>) [fast-method]
  5: (SB-INT:SIMPLE-EVAL-IN-LEXENV (CL-IRC:READ-MESSAGE-LOOP *CONN*) #<NULL-LEXENV>)
  6: (EVAL (CL-IRC:READ-MESSAGE-LOOP *CONN*))

While in the REPL I see:

UNHANDLED-EVENT:3672562852: RPL_MYINFO: irc.tinyspeck.com duncan_bayne "IRC-SLACK gateway"

I'm not sure what I'm doing wrong here; I'm fairly sure it's not my hooks, because the problem persists even if I disable them all.

Also, I can use the connection as expected - say, joining a channel and sending messages - provided I don't try to start the message loop.

At a guess, I'd say Slack is responding to connection with an unexpected message?

See if you get any other errors if you change the destructuring-bind (in event.lisp line 149) to `(nickname &rest welcome-message)`. The `WELCOME-MESSAGE` doesn't seem to be used for anything, so maybe the dev just forgot the &rest and it happened to work in his test-cases. — jkiiski, May 18 '16 at 13:09
If you can fix it and submit a patch, that's great. Otherwise, the last time I tried to something with IRC, I used https://github.com/Shinmera/colleen and it worked. — coredump, May 18 '16 at 13:39

score 5 · Accepted Answer · answered May 18 '16 at 21:45

The fix as suggested by @jkilski is to modify cl-irc to accept the slightly unusual (but probably standards-compilant?) responses from Slack:

(in-package #:cl-irc)
(defmethod default-hook ((message irc-rpl_welcome-message))
  (with-slots
        (connection host user arguments)
      message
    (destructuring-bind
          (nickname &rest welcome-message)
        arguments
      (setf (user connection)
            (make-user connection
                       :nickname nickname
                       :hostname host
                       :username user)))))

(in-package #:irc)
(defmethod default-hook ((message irc-rpl_namreply-message))
  (let* ((connection (connection message)))
    (destructuring-bind
          (nick chan-visibility channel &optional names)
        (arguments message)
      (declare (ignore nick))
      (let ((channel (find-channel connection channel)))
        (setf (visibility channel)
              (or (second (assoc chan-visibility
                                 '(("=" :public) ("*" :private) ("@" :secret))
                                 :test #'string=))
                  :unknown))
        (unless (has-mode-p channel 'namreply-in-progress)
          (add-mode channel 'namreply-in-progress
                    (make-instance 'list-value-mode :value-type :user)))
        (dolist (nickname (tokenize-string names))
          (let ((user (find-or-make-user connection
                                         (canonicalize-nickname connection
                                                                nickname))))
            (unless (equal user (user connection))
              (add-user connection user)
              (add-user channel user))
            (set-mode channel 'namreply-in-progress user)
            (let* ((mode-char (getf (nick-prefixes connection)
                                    (elt nickname 0)))
                   (mode-name (when mode-char
                                (mode-name-from-char connection
                                                     channel mode-char))))
              (when mode-name
                (if (has-mode-p channel mode-name)
                    (set-mode channel mode-name user)
                    (set-mode-value (add-mode channel mode-name
                                              (make-mode connection
                                                         channel mode-name))
                                    user))))))))))

I've applied to join the dev mailing list and will be submitting a patch shortly.

Error connecting to Slack IRC gateway

1 Answers1